Seismicity characteristics of the 2011 M9.0 Tohoku earthquake near the East Coast of Honshu in Japan  

作　　者：XUE Yan LIU Jie YU HuaiZhong LIU ShuangQing 

机构地区：[1]Institute of Geophysics,China Earthquake Administration,Beijing 100081,China [2]China Earthquake Networks Center,Beijing 100045,China [3]Earthquake Administration of Tianjin Municipality,Tianjin 300201,China

出　　处：《Chinese Science Bulletin》2012年第8期886-893,共8页

基　　金：supported by the National Basic Research Program of China (2008CB425704);the Eleventh Five-Year National Key Technology R&D Program (2008BAC35B05)

摘　　要：The spatiotemporal evolution of the M9.0 Tohoku earthquake sequence off the East Coast of Honshu in Japan on March 11,2011 and precursive seismic activity near the Japan Trench show that the earthquake sequence has foreshock-main shock-aftershock characteristics.Its foreshock sequence is characterized by a concentrated spatial distribution,low b value and the same focal mechanisms.Half an hour after the main shock,the two greatest aftershocks,with magnitudes of M7.9 and M7.7,occurred,followed by a rapid reduction in the strength of events.The aftershock activity was enhanced roughly two weeks and one month after the main event.This great earthquake ruptured bilaterally.Five hours after the main shock,the aftershock zone extended over a range that was 500 km in length and 300 km in width.A day later,the long axis of the aftershock area had expanded to about 600 km.Nine years prior to the 2011 earthquake,the seismicity in the location of the seismic source for this event enhanced significantly,with the extent of this area of enhanced seismicity being roughly equivalent to the aftershock zone.The spatiotemporal evolution of the M9.0 Tohoku earthquake sequence off the East Coast of Honshu in Japan on March 11,2011 and precursive seismic activity near the Japan Trench show that the earthquake sequence has foreshockmain shockaftershock characteristics. Its foreshock sequence is characterized by a concentrated spatial distribution, low b value and the same focal mechanisms. Half an hour after the main shock, the two greatest aftershocks, with magnitudes of M7.9 and M7.7, occurred, fol lowed by a rapid reduction in the strength of events. The aftershock activity was enhanced roughly two weeks and one month after the main event. This great earthquake ruptured bilaterally. Five hours after the main shock, the aftershock zone extended over a range that was 500 km in length and 300 km in width. A day later, the long axis of the aftershock area had expanded to about 600 km. Nine years prior to the 2011 earthquake, the seismicity in the location of the seismic source for this event enhanced significantly, with the extent of this area of enhanced seismicity being roughly equivalent to the aftershock zone.

关 键 词：地震活动特征 日本海沟 东海岸 东北 地震序列 余震活动 时空演化 空间分布 

分 类 号：P315.5[天文地球—地震学] U656.1[天文地球—固体地球物理学]